🚀 day 11 – Fixing Ghost Group ID Issue in Linux (DevOps Practice)

Today I encountered and resolved a real-world Linux user/group issue — a ghost group ID left over after deleting a group (docker) that my user was still a member of.

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⚠️ The Problem

After running:

sudo groupdel docker

Then checking:

groups

I saw:

groups: cannot find name for group ID 137
137 devs

This meant the group with GID 137 was deleted, but my session still referenced it.

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🔍 Investigation

Step 1: Checked active groups

id ritesh

Step 2: Validated /etc/group

getent group | grep 137   # No result
getent group docker       # docker:x:1011:ritesh

Confirmed that group 137 no longer existed.

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✅ The Fix

Step 1: Reassign valid groups

sudo usermod -G sudo,docker ritesh

Step 2: Log out and log back in

This cleared the ghost group from the session.

Step 3: Recheck

groups
# Output:
ritesh sudo docker

Step 4: Verified with:

id ritesh
# Output:
uid=1000(ritesh) gid=1000(ritesh) groups=1000(ritesh),27(sudo),1011(docker)

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🧠 Key Takeaways

• Linux can retain ghost group IDs in active sessions after groupdel

• Use id and getent group to debug group memberships and GIDs

• usermod -G helps reset valid group memberships

• Always logout/login to refresh session and group context

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📌 Useful Commands

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🔗 Related Links

• 🔒 Day 10 – SSH & Secure Access

• 📁 GitHub Repo – DevOps Journal

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🧠 Quote of the Day

"Understanding groups and permissions is not just a Linux skill — it's a DevOps superpower."